1. Field of the Invention
The present invention relates to a zoom lens system used in a photographic camera, especially a portable lens-shutter (compact) camera in which a photographing lens can be accommodated in a camera body thereof.
2. Description of the Prior Art
Unlike a zoom lens system for a single lens reflex (SLR) camera which requires space for a quick-return mirror behind the photographing lens system, a zoom lens system for a compact camera does not require a long back focal distance. As a zoom lens system which has a fewer requirements on the back focal distance, a telephoto-type optical system, having a positive lens group and a negative lens group in this order from the object, has been generally used.
In such a telephoto-type optical system, in the case where the zoom ratio is relatively small, e.g., approximately 3 or 4, a three-lens-group arrangement including a positive lens group, the other positive lens group, and a negative lens group in this order from the object, is employed.
In recent years, a zoom lens system for a compact camera has been required to have a higher zoom ratio and further miniaturization.
For example, Japanese Unexamined Patent Publication (JUPP) No. Hei-06-194573, JUPP No. Hei-09-120028, and JUPP No. Hei-10-268191 have disclosed a miniaturized zoom lens system with a higher zoom ratio; however, the zoom lens systems thereof are devised to mainly miniaturize the zoom lens system in the optical axis direction with respect to a photographic position of the zoom lens system and a fully-retracted position thereof. In other words, none of the zoom lens systems of the above publications has considered miniaturization of the zoom lens system in a direction perpendicular to the optical axis, i.e., in a radial direction of the zoom lens system.